The present invention relates to the field of guidance for the insertion of a biopsy needle and, more specifically to providing assistance for ultrasound guided needle biopsy.
For a needle biopsy, a biopsy needle has to be inserted into an anatomical target to remove a tissue sample. Ultrasound guidance is routinely used, for example, for breast needle biopsies. The real-time ultrasound images allow the physician to locate the target and to monitor the needle position.
Typically, the procedure is performed xe2x80x9cin-planexe2x80x9d, that is, the ultrasound imaging is performed in a plane. In accordance with known procedures, with the ultrasound transducer being in a position where the target is visible in the image, the insertion point of the needle is chosen on the intersection of the ultrasound plane and the patient""s skin surface. The needle is oriented so that it lies in this plane and points towards the target. When the needle is now inserted, it will appear in the ultrasound image, and the progress along its path towards the target can be monitored.
One difficulty with performing an ultrasound guided needle biopsy in this way is to correctly position and orient the needle to be in the same plane with the ultrasound image. Mechanical needle guides are commercially available to facilitate this task. They are clipped onto the transducer and constrain the movement of the needle so that it is forced to stay in a plane aligned with the transducer. Even though the needle can now reliably be placed in the plane of the ultrasound image, many physicians find the rigid constraint imposed by the use of this mechanical guide too inflexible and consequently do not use it. They want to be able to make corrective adjustments to the path of the needle as it approaches the target, and this is not easily possible with the constraints of the mechanical needle guide. Nor is it possible to insert the needle at some distance from the ultrasound imaging transducer, which is desirable for shallow needle angles because the mechanical guide constrains the needle entry point to be close to the transducer.
It is an object of the present invention to makes in-plane needle alignment easy while preserving the full flexibility of a free-hand procedure.
A method for video assistance for ultrasound guided needle biopsy of a patient, includes the steps of obtaining an ultrasound image of said patient in an ultrasound imaging plane by way of a transducer head; obtaining a body surface video image of said patient including an area wherein said ultrasound imaging plane intersects said body surface, by way of a video camera mounted on said transducer head and having an optical axis lying in said ultrasound imaging plane such that said ultrasound imaging plane corresponds to a line in said video image; and overlaying graphic markers onto said video image for indicating said ultrasound imaging plane as a line of possible entry points for needle biopsy.
In accordance with another aspect of the invention, apparatus for video assistance for ultrasound guided needle biopsy of a patient, comprises: ultrasound imaging apparatus, the imaging apparatus including a transducer head for obtaining ultrasound data from the patient in an ultrasound imaging plane for forming an ultrasound image of actual anatomical structures in the patient; a video camera mounted on the transducer head for obtaining a body surface video image of the patient including an area wherein the ultrasound imaging plane intersects said body surface, the video camera having an optical axis lying in said ultrasound imaging plane such that the ultrasound imaging plane corresponds to a line in the video image; graphic markers overlaid onto said video image for indicating said ultrasound imaging plane as a line of possible entry points for needle biopsy; and an augmented reality visualization system coupled to their ultrasound imaging apparatus for providing augmented images enabling visible structures in the ultrasound image to appear in the location of corresponding ones of the actual anatomical structures.